I suggest Aperture, Easymode-Halation or Kurozumi-Royale. Those are the 3 best to me and I often swap between them depending on my mood.
Kurozumi can be heavier on the GPU and requires you have integer scaling on to prevent spacing weirdness.
Aperture is very light on the GPU but looks very good and is a thicker scanline.
Easymode-Halation is somewhere in the middle in performance but looks a bit more natural to a TV than a PVM like the other 2 are. Easymode-Halation also doesn't darken the image as much.

There is now an Atari800 core which includes support for the 5200. There is some setup required of course but it works very well. H.E.R.O. plays so good on it with a proper digital controller, so responsive and 2 buttons :)

This is what drew me to Launchbox. It's easy to get the basics up and running like box art and screenshots and easy to import your games assigned to the appropriate emulators. Then from there you can get more fancy and complicated as you feel more comfortable with it.
The only way it could be made more easy would be to include the emulators with the program but that would go against many if not all emulator licenses because of Launchbox's commercial non open source status.

You can use the same art in Launchbox and you do not need to duplicate your art folders. In Launchbox simply edit each platform and in there you can set the paths to each art type folder to your Hyperspin art.

That's cool to hear that RetroFE is easy to setup and to be fair I have not tried it and I have no intention of it but who knows what the future holds :)
There is certainly plenty of room for multiple front ends because as good as Launchbox is it is not for everyone for a couple of major reasons. One, it is a paid program to get all the features and two, it can be a bit of a system resource hog.
I hope my post didn't come off as a Launchbox vs other front ends because that was not my intention. I only intended to point out that ease of use for the end user especially for those new to emulation and front ends is a big deal and it's part of the reason that Launchbox right now has so many users willing to pay for that convenience.

Just some friendly advice to the devs of HyperSpin and RetroFE.
Make setup of emulators and rom management easy and your frontend will be plenty successful. This is pretty much the sole reason Launchbox has so many users now. With little to no frontend experience a user can have their games with art work up and running in 5 to 10 minutes

AttractMode is a front end and pretty good for a very streamlined set in stone setup on lower end hardware. Managing a games collection with it is a pain in the ass though so you don't want to be adding and removing games, that is why I said if your game selection is set in stone.

Shaders are such big and subjective topic. There are a lot of different shaders to choose from and what one you use will depend on what kind of look you want, your display type and system specs.
Any shader will technically work with any core but depending on the type of game it will look better or worse. A shader that looks great with a 2D sprite based 16-bit game will probably look awful with a 3D polygonal 32-bit game.
A high end CRT shader such as Royale or the Kurozumi edit of Royale looks really nice on TVs and monitors greater than 1080p but on 1080 or less it may not look the way it was intended due to lower pixel density. Another CRT shader such as Easymode-Halation looks really nice on a TN panel but on an IPS panel it may look really bloomed out.
You also may not like the CRT scanline look and maybe you want the smoothed out modern look that XBR shaders provide but those types of shaders look best on "cartoonish" and "stylized" games like a Mario or Zelda game. But games with a more "realistic" and "detailed" look such as Final Fantasy III those smoothing shaders don't look so good.
Then there is performance hit, while emulators are CPU driven shaders are GPU driven and a heavy shader such as Royale or Kurozumi you will need a decent GPU. An on board Intel video chip will not be able to handle those shaders at all and you will need to look for a lighter shader such as CRT-Pi or Hylian.

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About EmuMovies

EmuMovies is a project that started in 2005 to create video previews of video games to replace static screenshots in Gaming Front Ends. Since then the collection has grown to well over 20,000 video game previews for Arcade, Console, Handheld and even Computer based game systems. In addition to the Video Snaps that started everything we also have vast amounts of additional content for many systems. We partner with most front end designers with artwork content and integration solutions.